Nuclear Electromagnetic Pulse Research Articles

A New Strategy is Needed to Solve the 50-Year-Old Problem - EMP Protection of Critical Civilian Infrastructure

The problem of the destructive effects of High-Altitude Electromagnetic Pulse (HEMP or EMP) on electronic and electrical equipment has been well known for more than 50 years. All military equipment and critical equipment of special governmental services are reliably protected from such influences. There are many companies on the market that manufactures numerous EMP protection means that meet the requirements of military standards. It would seem that in such a situation, critical civilian infrastructure facilities (electrical power systems, water supply systems, communications, large medical centers, banks, etc.) should also be protected against EMP. But it turns out that this is not the case! Nowhere in the world are critical civilian infrastructure still protected from such impacts! Why? The main reason is an attempt to use well-known military strategies, methods and protection means for protecting civilian infrastructure. This article proposes new protection strategies and methods for the civilian sector.

Simulation study of electromagnetic protection of ignition chip

The purpose of this paper is to study the adaptability and enhancement methods of ignition chips in complex electromagnetic environments. In this paper, combined with simulation and calculation technology, we first establish the electromagnetic–electrical–thermal coupling simulation model of ignition chips and analyze the influence of two electromagnetic environments, continuous electromagnetic wave and nuclear electromagnetic pulse, on the electrical–thermal coupling in the bridge area of the ignition chip. The results show that a continuous electromagnetic wave field strength of 1200 V/m, irradiated for 5 s, a nuclear electromagnetic pulse with a rise time of 5 ns, a half-height width of 24 ns, and a leg wire length of 350 mm will cause the ignition chip to fire accidently. In order to suppress its accidental firing, the electromagnetic protection is enhanced by using parallel Transient Voltage Suppressor (TVS) diodes. It has been shown that parallel TVS diodes provide good protection against both continuous electromagnetic waves and nuclear electromagnetic pulses. In particular, the peak induced current decreases by more than 64.7% during the action of continuous electromagnetic waves, and the maximum temperature in the bridge area decreases by 54.34% during the action of nuclear electromagnetic pulses.

Impact Analysis of High-Altitude Electromagnetic Pulse Coupling Effects on Power Grid Protection Relays

Protection relays are important equipment used for protection, control, and metering functions in the power grid. These relays are used to protect critical and difficult-to-replace equipment, like generators, transformers, and capacitor banks. Once the protection devices are disturbed or damaged, a high risk of power generation interruption occurs. Therefore, it is important and necessary to study the relay’s immunity to electromagnetic pulse (EMP) events. As a preliminary step toward empirical experimentation on actual equipment, this manuscript outlines an economical and efficient methodology for evaluating the impact of an EMP. An impedance measurement strategy was employed to model the equipment, setting the stage for subsequent immunity analyses. These analyses included the pulse current injection (PCI) method, which utilized an injecting probe to introduce the transient, and frequency domain electromagnetic (FEKO) simulation, which integrated electromagnetic coupling effects into the transient simulation. The impedance measurement and simulation results in this paper provide a reliable basis for gauging equipment performance in the face of HEMP threats. The results obtained using the PCI and FEKO simulations demonstrated the performance of different port responses under a high-altitude EMP, indicating the requirement for some protection to ensure the reliable operation of relays.

A hybrid simulator with novel bicone-wire grid antenna.

The simulator is an indispensable device for the study of high-altitude electromagnetic pulse (HEMP) effects. In order to improve the quality of the electric field waveforms of the HEMP simulator, we carried out simulation and experimental studies for the biconical-wire grid antenna. A new bicone-wire grid antenna HEMP simulator was designed by using skeletonized cones instead of solid cones, which can substantially improve the mobility of the simulator. The effects of different aspect ratios and different cone structures of the simulator on the waveform and distribution characteristics of the electric field were analyzed. The accuracy of the simulation results was verified by testing the bicone-wire grid antenna simulator with the new structure. The results obtained are as follows: First, the simulator can provide a HEMP environment compliant with the International Electrotechnical Commission (IEC) standard in an area of 5 × 6 × 2m3. Second, the simulator possesses optimal waveform quality and working space among simulators with different aspect ratios. Finally, the influence of using skeletonized cones instead of solid cones on the simulator's electric field waveforms is negligible, and the mobility of the new simulator is significantly improved compared to the original simulator.

Analysis on the low-frequency electromagnetic pulse coupling to horizontal electrically short lines

In this study, we investigated the coupling features of the nuclear electromagnetic pulse (NEMP) on overhead cables in the middle-and-far regions, different from the transmission line model commonly used for field-line coupling in high-frequency cases, using a simpler lumped approximation to solve the electrically small size model in low-frequency cases. To verify its effectiveness, a simulation model with the same conditions was set up using the software of Computer Simulation Technology (CST), and cable coupling experiments were performed in a laboratory environment using a bounded-wave electromagnetic pulse simulator. The calculated results of the lumped approximation circuit were compared with the CST simulation and measured results, and the agreement was good. The results also shows that the load exhibits a differential response in the case of the low impedance and it is consistent with the excitation signal in the case of the high impedance. Finally, some more experiments were constructed to analyzed the effect of different cable parameters on the cable load response through experiments, and the experimental results are also in general agreement with the theoretical analysis, in which the induced signal of the low-impedance load is mainly determined by the magnetic field in the direction normal to the cable and the ground loop and the induced signal of the high-impedance load is mainly determined by the electric field in the direction of the height of the cable erection.

Analysis of Immunity of Relay Protection Equipment Under High-Altitude Electromagnetic Pulse

Analysis of Immunity of Relay Protection Equipment Under High-Altitude Electromagnetic Pulse

Response characteristics of a ZnO arrester under nanosecond electromagnetic pulse

Zinc oxide arresters, a major type of overvoltage protection equipment in power systems, can suppress transient lightning overvoltage, operation overvoltage, and other types of power surges. However, the response characteristics and protection effects under nanosecond pulses, such as those in a high-altitude electromagnetic pulse conduction region, remain unclear. Therefore, the surge protection performance of arresters should be properly understood, and high-performance arresters should be developed. In this study, critical parameters, including overshoot peak voltage, residual voltage, response time, and voltammetry characteristics of a representative 10 kV ZnO arrester under nanosecond pulses, were obtained using a double exponential pulse current injection source. The overshoot peak voltage of this arrester under a nanosecond pulse is 2.19 times of lightning impulse residual voltage, and the residual voltage ratio under a nanosecond pulse is 4.31. The average response time is approximately 45 ns, and the response time is independent of the nanosecond pulse amplitude. Furthermore, an electromagnetic transient model of this type of lightning arrester is established based on the CIGRE guidelines, as well as a method to determine the key parameters. The model can simultaneously account for the response characteristics of the small current region and the conduction region of the arrester, which properly agrees with the experimental results.

Dynamic Numerical Analysis of Interactions Between High-Altitude Electromagnetic Pulse and Power Grid

Dynamic Numerical Analysis of Interactions Between High-Altitude Electromagnetic Pulse and Power Grid

Assessing the vulnerability of solar inverters to EMPs: Port testing, PCI modeling, and protection strategies

Renewable energy sources are becoming an ever-larger contributor to the power grid. These renewable energy sources depend upon the power electronic devices, specifically inverters, being essential for connecting Photovoltaic (PV) generation to the grid. However, the Electromagnetic Pulses (EMPs) caused by the high-altitude nuclear explosions can generate fast broad-band pulses with nanosecond rise time, potentially causing damage or destruction to electronic components. To assess the vulnerability of PV inverters to high-altitude EMPs, the port testing and Pulsed Current Injection (PCI) modeling schemes are proposed based on the port impedance analysis. Wide-band frequency measurements are achieved by fusing impedance results from three vector network analyzers. Then, a PCI model is used to simulate the induced response to EMP, with two typical immunity levels of EC5 and EC8 tested. The experiment successfully excites the induced voltage and current under EMP, where the voltage and current can reach 1500V/40A and 8000V/150Aunder EC5 andEC8, respectively. The port vulnerability analysis results demonstrate that only some ports can survive under EC5. To defend against the impact of EMP, three protection strategies are discussed.

Dispersive propagation of nuclear electromagnetic pulse in the ionosphere

Introduction: On the propagation path to the satellite, the ionosphere will distort the nuclear electromagnetic pulse (NEMP) and change its physical properties.Methods: This paper proposes a method for calculating the propagation of NEMP to the satellite. The method decomposes NEMP into the superposition of simple harmonic waves, and each simple harmonic wave is calculated separately in the ionosphere. With the consideration of different time of arrival and critical frequency of the ionosphere, the NEMP after propagating in the ionosphere is obtained by superposition of simple harmonic waves in time domain rather than the inverse Fourier transform which will erase the time domain information.Results: The results show that NEMP is dispersive in ionosphere with the pulse broadened, the speeds changed and the bandwidth narrowed. The time-frequency spectrum can provide the frequency band where the signal energy is located.Discussion: Our proposed method provides a simple and effective way to calculate the NEMP propagation in the ionosphere, which should afford help to the design of NEMP receivers and the selection of satellite orbit altitude.

Development of a 3 MV coaxial peaking capacitor for large-scale electromagnetic pulse simulator.

Coaxial peaking capacitor is a key component in high-altitude electromagnetic pulse (EMP) simulators with fast front pulse output. It poses significant technical and engineering challenges in limiting radiation field amplitude and test space. This paper presents the design and testing of a 180 pF, 3 MV coaxial peaking capacitor with improved insulation performance. In the insulation design, the length of the dielectric film is extended to reduce the background electric field on the flashover path. The electric field threshold obtained from image diagnosis is used as a reference. During capacitor testing, the insulation characteristics are diagnosed using both direct and indirect methods. The voltage measured by a D-dot probe, the output waveform of the Marx generator in the primary source, and the radiation field waveform are analyzed to understand the flashover characteristics of the capacitor and to improve the reliability of the test results. The experimental results demonstrate that the peaking capacitor can operate stably at 3.0 MV. If flashover occurring on the dropping edge of the pulse is permitted, the operating voltage can be greater than 3.7 MV without significantly affecting the radiation field waveform. The analysis on the surface flashover morphology of the peaking capacitor reveals that the flashover mainly occurs at the dropping edge of the capacitor's waveform, indicating that the damage to the film is not serious. This research significantly increases the working voltage of coaxial peaking capacitors and contributes to the development of high-altitude EMP simulation technology.

HEMP Protection of Power Systems in Electromagnetic Shielding Cabinet

High-altitude Electromagnetic Pulse (HEMP) has a significant impact on power systems. This paper simulates the HEMP coupling for three types of power cables in an electromagnetic shielding cabinet. Besides, this paper proposes the HEMP protection circuit design for 220 V AC and 24 V DC power. In a lightning conduction injection test, the circuit reduces the peak voltage by 12.1 and 14.2 times for AC and DC, respectively. In a pulsed current injection (PCI) test, the circuit reduces the transient peak current to less than 8.2 A for both AC and DC.

NEMP Protection of Antennas in Mobile Communication System: Simulation and Circuit Design

Nuclear Electromagnetic Pulse (NEMP) is highly destructive to mobile communication systems. This paper targets the RF front door of shortwave and ultra-shortwave antennas, simulates the NEMP excitation and coupling effect of two types of antennas (half-loop and whip) based on the CST Microwave Studio platform (CST), and proposes a circuit design for NEMP protection. The protection circuit reduces the transient peak current to less than 5 A in a standard pulsed current injection (PCI) test. The simulation model and the circuit design may be references for the NEMP/HEMP protection of mobile communication systems.

Research on the Coupling Effect of Communication Display Interface under Strong Electromagnetic Pulse

In the high-altitude electromagnetic pulse (HEMP) environment, high-intensity broadband electromagnetic pulse energy is transmitted to the display interface circuit through the interconnection cable, causing interference or damage to the internal electronic components and chips, resulting in various damage effects such as the display cannot be displayed normally, and even restart. To investigate the coupling effect of strong electromagnetic pulses on the display interface circuit, the existing field-line coupling model is utilized as the basis of this study, with a specific focus on the VGA interface. The influence of different terminal impedances on the coupling effect is examined, aiming to determine the significance of terminal impedances in the simulation estimation of interface circuit coupling response. A HEMP coupling signal loop model is established based on the signal loop defined in the VGA datasheet, replicating the normal working conditions of VGA. HEMP pulse injection experiments are conducted to compare the response waveforms of the simulated VGA interface equivalent impedance circuit model with the measured data. This allows the accuracy of the established equivalent impedance model to be verified using key parameters.

A Full-Wave-Transmission-Line Hybrid Method for Vertically Laid Shielded Cable Illuminated by HEMP

A hybrid method of full-wave-transmission-line approach is established to calculate the transient response of the shielded cable vertically laid to the ground when illuminated by a high-altitude electromagnetic pulse. In the approach, the induced current on the external sheath is evaluated by Holland's thin-wire finite-difference time-domain method, while the response of the inner conductor is solved by the classic transmission-line method at the same time. Using the proposed approach, the termination currents of both conductors are computed and analyzed to conclude the general rules and waveform characteristics in the specified situation. Evaluated results show that the hybrid method gets good accuracy and efficiency, and the variations of the currents with several parameters are studied.

The Statistical Characteristics Analysis for Overvoltage of Elevated Transmission Line under High-Altitude Electromagnetic Pulse Based on Rosenblatt Transformation and Polynomial Chaos Expansion

A High-Altitude Electromagnetic Pulse (HEMP) could induce very fast transient overvoltage (VFTO) with nanosecond level rise time and mega-volt amplitude, which severely threatens the electrical devices connected to the elevated transmission line. An elevated transmission line with different locations may suffer different levels of HEMP threat since the dip angle could influence the polarization of the HEMP wave. The combination of Rosenblatt Transformation and Polynomial Chaos Expansion (R-PCE) is introduced in this paper. With this method, the efficiency of calculating the overvoltage of an elevated transmission line under HEMP is improved, speeding up 24.75 times. The influence of different factors (dip angle, elevated height, and earth conductivity) on the overvoltage of elevated transmission lines applied in power systems is calculated and analyzed. The numerical result shows with 99.9% confidence that the overvoltage would be over 3.7 MV of amplitude and 6.7 × 1014 V/s of voltage derivative, which is much more rigorous than a lighting pulse. We also find that elevated transmission lines may have a larger HEMP threat in a small dip angle area. The corresponding data are shown at the end of the paper, which could be useful for relative researchers in pulse injection experiments and reliable evaluation.

Progress in developing high-altitude electromagnetic pulse simulators

Progress in developing high-altitude electromagnetic pulse simulators

Error Analysis of the Maximum Coupling for HEMP Illumination Tests With EUT Rotations

The maximum electromagnetic coupling is directly related to the polarization angle of the incident field in the highaltitude electromagnetic pulse (HEMP) illumination test. Aimed at the linear system, this letter analyzed the test error of the maximum coupling corresponding to the change of the angel between the polarization direction and the direction of the equipment under test (EUT) in EMP illumination tests. Characterized by EM norm, quantization estimation formula of the maximum coupling test error under illuminations with EUT Rotations is deduced. The results show that the maximum measurement accuracy is the cosine of 1/2 of the maximum rotation angle of the EUTs. At last, a test scheme of 5 illuminations (with rotations of the EUT and the rotation angle of each rotation is 36∘) with 95% test accuracy of the maximum coupling of the method itself is recommended in this paper. The results can provide support for the design and evaluation of EM illumination test.

A Modeling and Design Methodology of Double Exponential Pulse Generator for Simulation-Based Conducted Disturbance Immunity Testing

In this paper, an equivalent circuit model of a double-exponential pulse generator is proposed for use as a time-domain noise source in high-altitude electromagnetic pulse (HEMP) conducted disturbance immunity testing. The analytic relationship between the proposed equivalent circuit model and the source pulse requirements expressed by the test standards is derived. Based on this relationship, a design methodology for the equivalent circuit model is proposed to extract the circuit components that satisfy the source pulse requirements, particularly in the form of source impedance and pulse waveform requirements. The proposed design methodology is applied to design an equivalent circuit model of the double exponential pulse generator with various test modes in the conducted disturbance immunity test. The designed double exponential pulse generator is applied to a simulation-based conductive disturbance immunity testing platform based on the International Electrotechnical Commission (IEC) 61000-4-24 standard to validate the effectiveness of the proposed equivalent circuit model and design methodology.

Failure Scenario of Power Supply Due to Conducted Electric Pulse From E1 HEMP

This article presents the effects of a high amplitude conducted electromagnetic pulse on the electrical behavior of a flyback switch-mode power supply. The electromagnetic pulse is generated by a current injection platform that is able to reproduce differential or common mode parasitic currents and voltages induced by the coupling between E1 high-altitude nuclear electromagnetic pulse and a global electrical network. In this article, injections are performed in differential mode until the destruction of power supply. Current and voltage measurements have been performed around each destroyed component during the injection. Finally, these destruction tests, associated with spice simulations and component analyses, permit to build a power supply destruction scenario with the component's failures chronology modeling. This scenario is the first step in order to model the susceptibility of power supplies during an electrical pulse injection.